Eye Flashcards
What are the functions of the eye ?
- Regulation of the amount of light entering the eye
- Focusing on light to form an image
- Conversion of light into neural activity
- Analysis of the visual image before it goes to the brain
What are the outer structures of the eye ?
- Cornea and Sclera (white area)
What is the pigmented area ?
- ciliary body, Iris, ciliary process, and choroid
Neural Retinal Structure of the eye
- non-visual part of retina
- retinal pigmented epithelium
- fovea
photosensitive part of the retina
What are the chambers of the eye?
Anterior, Posterior, and Vitreous
Anterior Chamber
- infront of the iris and the pupil
- filled with aqueous humor
Posterior Chamber
- chamber around the lens
- filled with aqueous humor
Vitreous Chamber
- behind the lens
- filled with gelatinous vitreous humor
What are the three layers of the eye ?
Retinal, Choroid Layer, and Corneo-scleral layer
Retinal Layer
- Innermost Neural Layer
- Neural Retina
- Retinal Pigment Epithelium
Choroid Layer
- Middle Vascular Layer
- Choroid, Iris, and Ciliary Body
Corneo-scleral Layer
- Outer Fibrous Layer
- Cornea and Sclera
Choroid
highly vascularized, pigmented, loose connective tissue
Ciliary Body
- regulates fine focus by adjusting the shape of the lens, via parasympathetically innervated ciliary muscle
Ciliary Processes
source of aqueous humor –> goes into the anterior and posterior chambers
Zonule Fibers
- fine ligaments connecting ciliary body to lens
Iris
regulates amount of light entering eye by changing size of pupil
Dilator Pupillae Muscle is innervated by
- sympathetically
Constrictor Pupillae Muscle are innervated by
- parasympathetically
Where is most of the light focusing is done by ?
Cornea
Lens
- biconvex transparent avascular tissue, there is no blood supply which is why you can have a lens replaced
What are the roles of the lens ?
- provides fine focus of visual image by changing shape via ciliary muscle
What is the outer capsule of the lens composed of ?
- thick basement membrane
What does the anterior epithelial cells of the lens differentiate into ?
- elongated fiber cells
Opacities
cataracts
What is the first layer of the retina ?
Inner limiting membrane
What is the inner limiting membrane ?
- inner limiting membrane basal lamina of Muller’s cells
What is the second layer ?
- Ganglion Cell Axons
What goes on in ganglion cell axons ?
- optic nerve fibers from ganglion cells
What is the third layer ?
- ganglion cell bodies
What is ganglion cell bodies?
ganglion layer cell bodies of large multipolar neurons synapsing with inner plexiform and axonal process to optic nerve
What is the fourth layer ?
Inner synaptic layer
What does the inner synaptic layer ?
inner plexiform layer that contains neuronal processes
What is the fifth layer ?
Inner nuclear layer (interneurons)
What is the inner nuclear layer (interneurons) ?
inner nuclear layer contain nuclei from Muller’s, amacrine, bipolar, horizontal and interplexiform cells
What is the sixth layer ?
Outer Synaptic Layer
What does the outer synaptic layer ?
Outer plexiform layer processes of photoreceptor cells
What is the seventh layer ?
- outer nuclear layer ( photoreceptor cell bodies )
What does the outer nuclear layer (photoreceptor cell bodies) do ?
- outer nuclear layer from nuclei of rods and cones
What is the eighth layer ?
outer membrane layer
What is the outer membrane layer?
- outer membrane formed by row of zonulae adherence from Muller cells
What is the ninth layer ?
- rod and cone photoreceptor outer segments
What does the rod and cone photoreceptor outer segments ?
- rods and cones receptor cells for light and color. Rods for light/dark and cones for color
What is the 10th layer ?
retinal pigment epithelium
What is the retinal pigment epithelium ?
- pigment layer of retina forms blood retina barrier, absorbs excess light and phagocytize discs from rods and cones
What is the role of the Muller’s cells ?
- supporting cells
What is the role of the horizontal cells ?
- spread signals
What happens when there is retinal detachment ?
- coming apart
- curtains and flashes of light because of the separated receptors from the pigment layer
Retinal Pigment Epithelium
- nutritional support for photoreceptors
- absorbs stray light
- phagocytosis of shed photoreceptor outer segments
Photoreceptors
- phototransduction to convert light into neural activity
Interneurons
- spread them out
- Process neural signals
Ganglion cells
- transmit visual signals to brain
- via optic nerve
Fovea (macula)
- light is suppose to be focused
- back of the retina in line with visual axis
- contains no blood vessels
- all cones
Optic Disk or Papilla
- no rods and cones
- origin of the optic nerve
- blindspot
Ora Serrata
- anterior most part
- beginning of photoreceptors
What happens when zonula fibers are contracted ?
- The ciliary muscles are relaxed
- lens thin
- far vision
What happens when zonula fibers are relaxed ?
- contract the ciliary muscles
- lens are thick
- close vision
Macula Degeneration
- loss of the fovea function
What is the outer surface of the eyelid covered by ?
- thin skin
What is the inner surface of the eye lid covered by ?
- conjuctiva, goblet cells and no hair
- stratified columnar epithelium with goblet cells
What does the eyelid contain?
- tarsal plate ( fibroelastic connective tissue)
- Orbicularis Muscle
- Large Sebaceous
- Small Sebaceous
- Moll Sweat Glands
What is the large sebaceous gland of the eyelid ?
Meibomium glands, not with hair
What is the small sebaceous gland of the eyelid ?
Zeis Glands, with hair